"As the novel progresses, Mia begins to suspect that many people around her suffer from brain damage, leaving the reader with an exciting sense of unease." - Publishers Weekly

"(P)unchy and provocative (.....) Dramatic reversals and disclosures play out in the confusion, but the difference of this tensely executed thriller is that its unreliability seems less like a literary device than a hard, biological fact." - Sam Sacks, Wall Street Journal

Please note that these ratings solely represent the complete review's biased interpretation and subjective opinion of the actual reviews and do not claim to accurately reflect or represent the views of the reviewers.
Similarly the illustrative quotes chosen here are merely those the complete review subjectively believes represent the tenor and judgment of the review as a whole. We acknowledge (and remind and warn you) that they may, in fact, be entirely unrepresentative of the actual reviews by any other measure.

Schoolteacher Mia wasn't particularly happy in her marriage to headmaster Frederik Halling for the longest time, but when You Disappear opens, as they are on vacation on Majorca with their teenage son Niklas, everything seems great.
For the past three years Frederik has turned a new leaf.
He isn't sleeping around anymore, he's attentive at home.
Mia and Frederik finally have the marriage she longed for with the man she recognized twenty years earlier, when she was just twenty-two, as the love of her life.
Things come crashing down pretty fast, then -- starting literally with the minor car crash they have as Frederik gets carried away driving.
After that Frederik doesn't quite fall off a cliff, but he does take a tumble and smashes his head and is taken to hospital.
He's not badly injured, but they do discover something: he has a brain tumor, which likely triggered his erratic behavior.
Indeed, it likely has been affecting his behavior and personality for a while now, as it has been growing.
So the Frederik Mia has been so happy with the past three years isn't quite the man she thought he was; it's all thanks to the brain tumor.
It made him a changed man -- except that's he's now too changed: out of control, irresponsible, unreliable.
Removing the tumor is a fairly straightforward procedure, but will bring about with it further change.
Mia is not thrilled by what she's facing, and what she might have to face -- and she already has one foot out the door:

I decide, as I've already done several times in the last few days, that if the operation doesn't cure Frederick, I'll stick with him for a year and a half, maximum.
Only until he's gotten as far as he can with rehab; after that it's over.
It feels good for me to think that.
It's necessary to have an emergency exit.

The surgery goes fine, but Frederick remains impaired; even after four months of steady recovery "he seems just as alien as he was in the month before surgery".
Still, she can fondly look back on those three last years, when he was: "a dream of a man" .....
Except that whatever changed in him that made him more agreeable to Mia also made him take wild risks with funds of the private school that he ran, leading to huge losses that likely will bankrupt it and several of those associated with it.
Civil liability is a given -- Mia and Frederick will lose their house and most of their belongings -- but there's also a criminal case here, and here the issue is ultimately one of mens rea -- was Frederick aware of what he was doing, and that it was wrong.
Mia is faced with the awkward fact that keeping her husband out of jail means claiming that the wonderful man he was over the past three years was, in fact, not the 'real' Frederick, but a brain-damaged one who acted in these ways only because a tumor was pushing against the wrong parts of his brain.
Mia joins a support group for brain-damaged families, and one of the others in the group is a lawyer who takes Frederick's case.
Bernard was in a terrible car accident with his wife Lærke eight years earlier, and while he has recovered well she is physically still damaged and acts and speaks at the level of a pre-schooler.
Bernard is devoted to his wife, but Mia is irresistibly drawn to him, and though he tries to keep her at a distance they can't help themselves; eventually they're involved in a passionate affair.
Frederick's case doesn't proceed very quickly, and Mia struggles dealing with the new/old Frederick, who behaves like a moody teen -- a bit much to take, since there's already one of those in the household.
(Mom leaving all the articles and books about neuropsychology and the like lying around doesn't help, as Niklas gleans enough to use the underdeveloped-brains-of-teens argument to explain and excuse his own actions.)
The in-laws are some help, but Mia can't stand them, so that complicates matters too.
There are some digs at the American legal system, as the criminal case against Frederick unfolds -- notably:

It's possible to find "experts" who will say anything for money, so to avoid that American state of affairs, the government has established a special group of forensic psychiatrists.

It's the medical reports that will determine his fate, the judges almost certain to defer completely to the professionals' judgment.
But while the case putters along in the background, Mia's account is much more focused on herself and her experiences -- her continuing frustrations with Frederick, her concern about her son, and her interest in Bernard.
Problematically, Mia is a pretty unpleasant character.
While apparently attentive to many of Frederick's needs, her account focuses on scenes of confrontation and misunderstanding -- and she often doesn't come out looking well in those.
Impulsive, blurting out things when she should remain quiet, not listening to what others are saying, she has a good hand in complicating their lives too.
She's also calculating -- and a typical deaf rationalization of hers is:

Neither of my friends has said that Bernard and I are doing anything wrong.
They know that we both give our spouses so much more than we get back.

At least she recognizes, early on, that all this has affected her and her son to the extent of changing their personalities too, and she even insists on their getting their brains scanned (sorry, no tumors ...).
Late in the novel, Jungersen also offers a nice (and wonderfully obvious) twist to the whole brain-damaged/personality-changing theme that runs through the book, as it considers the question of identity and character (and personal responsibility), of who is 'the real me', or 'the real you' and who do we want them to be.
Interspersed in the text are all sorts of articles and studies about different aspects of neurology and neurological damage, as well as some e-mails and similar things -- most not directly addressed in Mia's account, but many having a bearing on it.
Among them is part of an article claiming 'Storytelling's Crutch is Broken', arguing that: "Twentieth-century narratives have become inextricably intertwined with psychoanalysis" -- but psychoanalysis has now been exposed as: "an unscientific superstition on a level with astrology and numerology".
By relying on traditional psychoanalysis, modern fiction fails the reader -- worse than: "if authors had been educated in biology before Darwin or physics before Einstein".
Recent discoveries and advances in the science of the brain suggests completely different fundamentals, and by not fitting our fictions to these -- but rather making them the artificial constructs that fit outdated psychological paradigms -- all authors are offering is fiction as: "deception and opiate of the people".
Jungersen's novel is, of course, meant to reflect this: he has tried to write a novel that is closer to 'reality' -- at least as far as the mind works.
To some extent, this works -- but in depending so entirely on Mia's version (and understanding) of events Jungersen also limits how much he can do.
Writing from within Mia's mind -- except for the brief filler-material, the novel is entirely Mia's account -- he shows a process of dissolution: marriage, morals, personality, all are thrown into question.
Mia does not completely see what is happening to her -- though she is aware enough to get a brain scan -- but one of the creepier aspects of the novel is that she seems to be as (or more) brain-damaged than many of the characters she deals with, despite not having suffered any physical trauma.
(A possible suicide attempt -- she vehemently denies that's what it was -- just before Frederick became the (tumor-)changed man she adored is repeatedly mentioned, suggesting longer-term imbalance to her own mind, too.)
Mia wants the world to fit her expectations: as far as her relationships go, it's all about what she gets out of them, and whether her needs are being met.
Though not brain-damaged in the more apparent way many of the characters are, she's lacking in empathy or much understanding; this crisis seems to bring that even more to the fore.
She's clearly not completely 'right in the head' -- but then few people are.
You Disappear raises interesting questions about how we perceive the world and others, about personal identity and behavior, and about the overwhelmingly subjective nature of our relationships.
In this regard, it is an entirely successful novel -- yet with its odd pacing and first-person perspective is not entirely likable, nor nearly as convincing as it might be.